Range finder



Feb. 10, 1953 s, 5, sz wAcH 2,627,779

RANGE FINDER Filed April 21,'1949 23 FIG. l. 24 2/ INVENTOR. STANLEY S. SZELWACH 4 TTORNEY Patented Feb. 10, 1953 UNITED STATES PATENT OFFICE I signor to- Q-O-S Corporation, New York, N. Y.,

a corporation of New York Application April 21, 1949, Serial No. 83,777

3 Claims. (01. 88-2.4)

This invention relates to range finders used in conjunction with the precise focusing of cameras, and, more particularly, to range finders which are used separately and apart from the camera and which give the distance to a particular object (which distance may then be "used in focusing the camera or for any other purpose.) The range finders to which this invention pertains are small and for this reason are generally referred to as pocket range finders.

The principal objects of this invention are to provide a pocket range finder which is simple in construction, relatively inexpensive, small and compact in size, sturdy and reliable in operation and easy to manipulate. Among the other objects of invention are structural arrangements of parts-which will be described in the ensuing specification and set forth in the appended claims.

For the attainment of the foregoing and such other objects of invention as may appear or be pointed out herein, I have shown a preferred embodiment ofmy invention in the accompany-. ing drawing, wherein:

-Fig. 1 is. a sectional elevation along the longitudinal axis of the improved range finder;

' Fig. 2 is an end view of the device taken from the right of Fig. 1; and

Fig. 3 is a bottom view of the device.

The improved range finder comprises a base it! which is generally rectangular in outline but irregular in section, Fig. 1, and a shallow cover it] closed bythe base In. To receive the cover in this closing relationship, the base it is recessed to provide a peripheral ledge l l on which seat the end walls 2! of the cover, Fig. 1, and also the side walls (not shown). The width of recessed ledge I! is substantially equal to the wall thickness of cover 20 so that a flush, surface is presented, as best seen in Fig. 1; Cover 20 is removably held in place by a pair of screws 22 which clear through apertures-'inthe end walls 2| of the cover to be threaded in tapped holes [2, l4. Tapped hole l2 opens through an upstanding lugv l3 provided at the left end of base 10. Tapped hole I4 is disposed in a thickened portion I5 provided at the right end of the base.

, Cover 20 is pierced by apair of openings 23, 24 spaced a predetermined distance apart. Secured to the inner side of cover 2|] is a length of glass 25 which serves to close the interior of thedevice against dust. Opposite .light opening23, visa half-silvered mirror 3, while opposite-light opening 24 is an, ordinary mirror 2 or reflecting surface 34. Halfi-silvered mirror 3 is secured to a tubular eye+piece 6 which. is received in a round opening [6 in base It; A piece of glass 2 closes the inner bore l of eye piece 3. Rays entering the range finder atopening 23 pass directly through the half-silvered glass 3 to inner bore l of the eye-piece. Rays entering the range finder at the other opening 24 are reflected by mirror 34 to the inner surface of half-silvered glass 3 where they are again reflected to enter inner bore 1 of the eye-piece.

In the operation of the range finder, halfsilvered mirror 3 is fixed whereas mirror 34 is angularly adjusted (in a manner fully described subsequently) in determining the range or .distance of an object whose images enterspaced openings 23, 2'4. 1

Tubular eye-piece 6 has an annular shoulder 1 formed at the juncture of the eye flange 4 and the reduced cylindrical portion of the eyepiece. The eye-piece is inserted through opening IS with shoulder .labutting an annular boss I! provided. on the outer surface of base It. The eye-piece is held in position by a bowed split-ring spring .3 which is received in an annular groove}? in the outer surface of tubular eye-piece-B. Annular groove 8 is disposed relatively to the base Ill-so that one wall of annular groove, 8 is somewhat-below the inner surface of base [0. Bowed split-ringspring 9 is disposed in said annular groove 8 sothat it is in contact with both the upper surface of the groove and with said innersurface of .base Hl.

The compressive force urging the ends of splitring 9 into closed relation is sufliciently high to impose a frictional. drag on the eye-piece 6 preventing the eye-piece from beingfturn'ed by gripping the annular eye flange 4. However, it is necessary at the'factory'and often inthe field to angularly adjustthe position of the eye'- piece, or rathenthe half-silvered mirror 3 ecured thereto,v relative to the. "other? mirror:v .3 For this. purposaf'a hexagonal surface 5, see also Fig. '3, is provided externally of the tubular eye-piece between annular eye flange 4 and boss I! of the base. By means of a specialspanner wrench supplied with the range finder, eyepiece 6 may beturned against thefrictional drag of split-ring spring 9, -to adjust halfsilvered mirror 3 relative to reflecting mirror 34. Tubular eye-piece 6 is cut. substantially to provide an inclined annular surface 26 on which half-silvered mirrorj3 is seated and cemented. An opening 21 'is pierced through the wall of the tubular eye-piece to admit rays from the other mirror 34.

Reflecting mirror 34 is secured to the inclined leg 31 of a lever 30 which also has a substantially horizontal leg 32. Lever 30 also has a depending flange 38 by which it is pivotly mounted at 39 to an upstanding lug 28 on the base ID. A wire spring 29 coiled about pivot "39 "of the lever 30 with one end engaging the base 10 and the other end engaging the lever 30. tends to turn the lever in a clockwise sense, i. e., to depress horizontal leg 32 of the lever. This spring-urged depressing of leg 32 is resisted by the abutment of horizontal leg 32 with a button 42 projecting from upper end of a screw bolt 40 which 'is "threadedly received in an internally threaded bushing 41. Bushing 4| is secured to base 10 in' 'anman'mer similar to that previously described with reference to the eye-piece 6, That is, base ln hasa round opening E at the thickened portion of the. base, through which the bushing "4| passes. with a 'fiang e 41 at the lower end of the bushing abutting the base 10. Bushing M is retained-in place by :a 'bowed 'split-rln'g spring '49 which is received in an annular groove as of bushing 41 to firmly hold the "bushing against turning '(in the *manner described above with deference to bowed split-ring Q of eye-piece '5). However, flange 41 of the bushing jhas a-"hexagon'al surface 45, see :"Fig. which 'is adapted to receive a spanner wrench whereby the bushinglmay be'turned againstthe resistance of spring 4 9 for adjustment at the factory or in "the field. (Conveniently hexagonal surfaces :5 and '45 may :be made to common dimension :to .ireceive the same spanner wrench.)

A small disc 58 is secured to the lower :end of screw bolt '40. Disc :50 is knurled aroundits pe- -'ripheral rim 5! to facilitate turnin'g of the disc by the fingers. A calibratedqplateifl is secured tothe underside ordisc 50,:asfby-means of the 'screw13; "the calibration marks .being read with referenceto a referencemark M whichis provided on a lug fl which depends from base H] to ;position the tip of the lug substantially flush with thecalibrated plate 68. A lug-flfi-dependin'g from the underside of base lfl servesas a stop in cooperation with a small screw F56 in the disc '50. see Fig. '1,to halt thecou'nter-clockwise turning of disc 50, as viewed in Figc 3, with the zero mark ot-the disc calibrations (.60) opposite-reference mark-44 (as shown iniFig. 3)

It will be observed that-therangefinder construction as described above "may simply and easily be precisely "adjusted for exact image superimposition, either in'the factory or'in the field, while sightedon an: object through the :eyepiece with all adjustments efiected I fromoutside the casing. This maybe-accomplished in the following manner: the mirror 34, being solidly ailixed to the inclined leg 3l of the lever 30, may

be "adjusted'to anobject being sighted by turning disk Soto move the lever untit'the' image coincides "along one a'xls'cr'dimension with the image obtained in theeye piecethrough plate 3; while still sighting the' object 'the-spanner wrench may be implied to the fiattenedrportions '5 of the eye- 'piece. 'exteriorof the base-l0, and the eye piece rotated to exactly Isuperimpose the image along thefiother axis 'o'r dimension normal to the firstspite of the manufacturing tolerances and errors incident to fabrication of the lever, its pivot, and the securement of the mirror 34 which tend to prevent absolute parallelism between parts 34 and 3. Thereafter, the rangefindermay be preciselyin- 'dexed, either in the factory or in the field, while sighting an object and from the exterior of the casing, so as to permit accurate findings of distance to objects sighted in normaluseof thefinder. The indexing is performed in the following manner: the screw 43 is first loosened and the range finder-is then sighted on an object at considerable distance (over 300 feet, i. e. approachinginfinity) the disk 53 is'then turned so that screw 56 abuts the stop '46 andthe disk is held in this abutting relation 'by the fingers of one hand while the spanner wrench is applied to the flange A! to rotate the bushing 4|, disk 50 and screw 43 being held from rotation in the manner stated, until the image obtained in the eye-piece from mirror 34 'is superimposed exactly on that obtained through the plate 3, 'the coincidence of .the1image resulting from axial movement'without rotation of screw-d0, caused'by'turningof the bushing M; at this point the calibrated disk is turned sothat the index line forinfinity is aligned with :the marking 44*, without moving .disk 50 or screw 56 out of abutment with stop, and thejscrew '63 is tightened to fixedly-position the calibrated disk 60 with respect todiskiflxand screw at). Thereafter .the knurled disk 5010f the range finder is free to make one complete revolution before screw 58 again abuts stop 46, during normal range finding operatiomandthe-mirror. and its supporting'lever is precisely indexed'with respect to the calibrations on dial '60. so as to render accurate readings of the distance from the range :finder to any object sighted upon.

I claim:

1. In a pocket range finder :having anelongated casing provided with apair of spacedlight receiving apertures :in one wall thereof :and a mirror angularly disposed within. said casing pivotally supported for turning cadjustment .torefleet lightreceived through one :.of: said :apertures lengthwise of :the casing interior andathirdiaperture'in'the wall of said'casing opposite to said first mentioned walliandin alignment with said other aperture; a tubular eye-"piece irotatably mountedin said third apertureresilient means securing'ithe eye-piecettozthe wall of :said casing surroundingsaidthird aperture witha frictional force normally preventing rotation-until the-friction is overcome'lby agreater force applied to the eye-piece-externally of the casing, a half silvered plate fixedly secured to the inner end'of saideyepiece'at-an angle to the axis-thereof and extending across its bore between said aligned apertures i and positioned to receive the light -refiected by saidmirror and to reflect it -through said eye-piece in additiontopermitting the direct passage of light 'from said other aperture through the boreo'f saideye-piece whereby said plate is'rotatable-with said eyepiece about-an axis normal to the pivot axis of said mirror, and the half silveredplate, whilethe range finder is sighted on an object and adjusted for'coincidence in a dimension by means of said mirror, may be adjusted to coincidence in a dimension normal to said first dimension by the rotation of said'eyepiece.

2. In apocket range finder having an elongated casing provided with a pair'of spaced light receiving apertures inonewall thereof anda'mir- :ror."angularlyidisposed withintsaid' casingipivotal- 1y supported for turning adjustment to reflect light received through one of said apertures lengthwise of the casing interior and a third aperture in the wall of said casing opposite to said first mentioned wall and in alignment with said other aperture; a tubular eye-piece rotatably mounted in said third aperture, resilient means securing the eyepiece to the wall of said casing surrounding said third aperture with a frictional force normally preventing rotation until the friction is overcome by a greater force applied to the eye-piece externally of the casing, a half silvered plate fixedly secured to the inner end of said eye-piece at an angle to the axis thereof and extending across its bore between said aligned apertures and positioned to receive the light reflected by said mirror and to reflect it through said eyepiece in addition to permitting the direct passage of light from said other aperture through the bore of said eye-piece, said eye-piece being of tubular cylindrical form and being provided with a beveled inner end to which said half silvered plate is secured the cylindrical wall of said eye-piece near said beveled end being provided with an opening for passage of image light rays from said mirror to the inner surface of said plate, whereby said plate is rotatable with said eye-piece about an axis normal to the pivot axis of said mirror, and the half silvered plate, while the range finder is sighted on an object and adjusted for coincidence of images in a first dimension by means of said mirror, may be adjusted to coincidence of images in the dimension normal to said first dimension by the rotation of said eye-piece.

3. In a pocket range finder having an elongated casing provided with a pair of spaced light receiving apertures in one wall thereof and a mirror angularly disposed within said casing pivotally supported for turning adjustment to reflect light received through one of said apertures lengthwise of the casing interior and a third aperture in the wall of said casing opposite to said first mentioned wall and in alignment with said other aperture; a tubular eye-piece rotatably mounted in said third aperture, a flange formed at one end of said eye-piece for rotatably abutting an exterior surface of the casing and an annular recess spaced inwardly of said flange, resilient means securing the eye-piece to the wall of said casing surrounding said third aperture with a frictional force normally preventing rotation until the friction is overcome by a greater force applied to the eyepiece externally of the casing said resilient means comprising a split resilient ring seated in said recess and engaging the inner surface of the casing, a half silvered plate fixedly secured to the inner end of said eyepiece, said eye-piece being of tubular cylindrical form and being provided with a beveled inner end to which said half silvered plate is secured, the cylindrical wall of said eye-piece near said beveled end being provided with an opening for passage of image light rays from said mirror to the inner surface of said plate, said plate being thus secured to the inner end of the eye-piece at an angle to the axis thereof and extending across its bore between said aligned apertures and positioned to receive the light reflected by said mirror and to reflect it through said eye-piece in addition to permitting the direct passage of light from said other aperture through the bore of said eye-piece, whereby said plate is rotatable with said eye-piece about an axis normal to the pivot axis of said mirror, and the half silvered plate, while the range finder is sighted on an object and adjusted for coincidence of images in a first dimension by means of said mirror, may be adjusted to coincidence of images in the dimension normal to said first dimension by the rotation of said eyepiece.

STANLEY S. SZELWA-OH,

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,058,484 Mihalyi Oct. 27, 1936 2,186,806 Liebmann Jan. 9, 1940 2,284,831 McC'anlies June 2, 1942 FOREIGN PATENTS Number Country Date 606,777 Great Britain Aug. 19, 1948 

